The Earth Science Picture of the Day (EPOD) highlights the diverse processes and phenomena which shape our planet and our lives. EPOD will collect and archive photos, imagery, graphics, and artwork with short explanatory captions and links exemplifying features within the Earth system. The community is invited to contribute digital imagery, short captions and relevant links.

Lenticular Clouds Near Waddell, Arizona

Streamlined lenticular clouds are created by turbulence or strong upward air movement, associated with lee wave formation. Once formed, they simply ride the crest of updrafts but often appear stationary in the sky, even though noticeable surface winds may be present. This was the case on the day the above photo was taken. The most probable cause of the turbulence was a deflection of air up and over the White Tank Mountains (orgraphic influence), just north and west of the clouds' position. Note the wispy cirrus cloud downwind of the lenticular cloud at center. Whereas lenticular clouds are typically composed of very fine water droplets, cirrus clouds are made up of ice crystals. Photo taken on August 24, 2009.